1. Field of the Invention
The present invention relates to an apparatus to feed artificial snow to an artificial snow making device at a constant rate to precipitate artificial snow on a ski slope.
2. Description of the Invention
An artificial snow making device to precipitate artificial snow conventionally blows out artificial snow by using the centrifugal force of rotating impellers. Kinds of artificial snow mainly include: 1) plate snow; 2) flake snow; and 3) powder snow. In the case of 1) plate snow, the ice pieces are relatively large such that they do not adhere to a feeder while being fed into the artificial snow making device. However, as the size of the ice pieces becomes smaller from 2) flake snow to 3) powder snow, it tends to adhere to the feeder. The adhered ice pieces gradually grow larger and freeze such that the feeder eventually stops functioning.
Impellers 4 of a conventional artificial snow blower or a rotary valve of a feeder are formed around impeller rotary shaft 3 in the radial direction. As shown in FIG. 8, the bottoms of impeller 4 contacting impeller rotary shaft 3 form corner portions 26 at an approximately right angle. Corner portions 26 hardly catch large ice pieces 27 while fine ice pieces 27 tend to adhere thereto. As mentioned above, the adhered ice pieces grow and freeze into lumps of ice pieces 27. The lumps cause additional load to impellers 4 such that additional drive is required to maintain the rotation of impellers 4. Further, the operating surfaces of impellers 4 are reduced such that the performance is deteriorated. Finally, the entire device is frozen and stops. A skiing population prefers natural snow such as 2) flake snow or 3) powder snow such that this type of trouble is inevitable.
The present invention provides an apparatus which does not cause adhesion, growth and freezing of ice pieces, which tend to happen with quality artificial snow such as fine flake snow and powder snow, in a rotary valve as an artificial snow feeder at a constant rate.
To solve the above issue, according to the a first aspect, the present invention provides a rotary valve 1 to feed artificial snow at a constant rate, which includes:
cylindrical casing 2;
impeller rotary shaft 3 which is placed in cylindrical casing 2 in the length direction of the cylinder;
a plurality of impellers 4 which are arranged around impeller rotary shaft 3 at an equal distance from each other in the radial direction;
housing 24 which supports cylindrical casing 2 therein;
opening 25 for loading of artificial snow which connects the top portion of a wall of cylindrical casing 2 with the top portion of housing 24;
opening 7 for receiving compressed air which is formed on the side wall 6 of casing 2 at one end 5 of impeller rotary shaft 3 to receive said compressed air from a blower; and
exit 10 for artificial snow formed at the other end 8 of the casing side wall 9 to blow out artificial snow cut in a given amount with compressed air,
wherein the diameter 11 of impeller rotary shaft 3 is established to be about one half of the diameter 12 of cylindrical casing 2,
impeller 4 is connected with the adjacent impeller at its end contacting impeller rotary shaft 3 by a smooth surface of arched plate 14 having arc 15, and
an opening 7 for receiving compressed air on casing side wall 6 and an exit 10 for artificial snow on the other casing side wall 9 are arranged across from each other in arc 15 between impellers 4.
According to a second aspect, the present invention provides a rotary valve 1 to feed artificial snow at a constant rate in relation to the first aspect in which arched plate 14 having arc 15 is covered by coating layer 29 of a lubricating resin.
According to a third aspect, the present invention provides a rotary valve 1 to feed artificial snow at a constant rate in relation to the first and second aspect in which:
spaces on sides of impeller 4 between arched plate 14 having arc 15 and impeller rotary shaft 3 are hollow portions 16;
heater hole 17 is provided such that a heater is placed at the center of impeller rotary shaft 3 in the axial direction; and
heater hole 17 and each hollow portion 16 are connected via a plurality of thermal convection holes 18 which are formed in the radial direction to send the heat from heater hole 17 to each hollow portion 16.
According to a fourth aspect, the present invention provides a rotary valve 1 to feed artificial snow at a constant rate in relation to one of the first to third aspects in which ring grooves 19 are formed at both ends of the impeller rotary shaft, wherein ring seals are engaged to the ring grooves such that the sections between the ends of the impeller rotary shaft and the side walls of the cylindrical casing are air-tight.